Purification of 1-amino-2-chlor-anthraquinone



Patented Nov. 24, 1931 UNITED STATES WILLIAM GRAHAM wooncocx, HUGH anniinwinnwm amnscrma, mass enown BECKETT, AND JOHN THOMAS, or ermnemtoum'mseommnn,,nssrerrons mo scor- TISH DYES, LIMITED, OF GRANGEMOU'IHit-SUQTLANI) t I" I PURIFICATION or i-smmo-acniioannmannomnomi No Drawing. Original application filed September aim; fseriiiifin l;13%",624, ana iii cre t permit October a, 1925. Divided and this applicati dnjled'I1i1y 6, .1?29 Serial no. amass.

This invention relates to the manufacture of 1-amin0-2-chlor-anthraquinone.

It has for its object to provide a process for the preparation of this body in substan- 5 tially pure form.

In co-pending application No. 137,624 filed on September 24, 1926, there is described among other processes a method of separat ing into its different constituents a mixture of halogen-amino-anthraquinones .obtained by condensing (3-amino-4-halogen) -2-benzoyl-benzoic acid. This method of separation is based on the diiferent solubility of the two constituents in sulphuric acid of different concentrations. The isomer that separates out from 80 per cent. sulphuric acid,

anthraquinone and 2-amino-3-chlor-anthra-' quinone and also there have been several cases of the purification of vat dyestuffs from sulphuric acid. There is an element ofsurprise in the fact that anthraquinone-l-amino- Q-chlor can be purified by recrystallization from sulphuric acid in the fact that it is a strong basic substance and therefore of high solubility in acid and it could not be expected that it could easily be precipitated from the sulphuric acid, especially to obtain a high yield. In the separation of Q-amino-B-chloranthraquinone and 1amino-2011101 -anthra v quinone use may be made of the solubility of the l-amino-body in order to separate the 2- amino one by adding water until the 2 amino 3-chlor precipitated out while the 1-amino-2 chlor remained in solution, the 1-amino-2- chlor afterwards being recovered by drowning in water and filtration. In the separation bit ricia 1- jainin1o 5'2 chi'or arithraqluiriorre in acid referred- "to abovefthe acid is first diluted to when, the 'Q-amino{3 -chlor-anthraqui} none is separatedbfi'. 7 After this separation it is necessary to dilute" the} acid much fur ther, "preferably "to about 80%{to cause the '1-amino-2-chlor anthraquinone [to I separate f QfIn the facejo't thefabovepit'isnotto be expact-ed that it shouldbefpossible to purify anthraquinone-l ainino QsChlor "precipita-ting 'it from sulphuricacid, *foreirample of strengthabouti'ft) It is in fact a matter of definite ,surprisel'tliat 'l-a-mino-Q-clilor be purified lTL lilfiS W&y.. 2

'- Biieiu magmw a. are purification ei a L-amino-Qchlor amthraquinone, containing of 2-da'rnino-f3 chloflanthraquinone {and prepared'as' tor example by ring closing' 3 amino-4'=clilor 2-benzoyl bonzoic "acid with sfulfhuric acid followed by dilution of the aei lfortheseparati-on of the'major fpafrt of the content of the. 2-amino 3 chlor-anthraqiii'nonel dissolvih'g the crude ieainino- -2;fchloranthiaquino re in 94%"a'cid and startto dilute to'.r;70"%, the-strength of 80% must bepassedintermediately. When this strengthof reached, the traces of 2 a'mino-3-chlor anthraquinone present, however, are not precipitatedas migh'tb'e ex'pect Qdyfifid ion diluting, further, as soon as (0% acid is reached, ,the 'i' amino- Q-chlor-anthraseparatesout"pl d (lomllldtgt ly, while the traces ofr 2-amino-3-chlor anthraquinone still remainin solution;

To recapitulate, in the first separation the 2-amino 3 chlor anthraquinone comes out first,.an'd itiisineces 'saryito dilute to about 50 v before the I11aininozchlor anthraquinone can be got'out, whereasjn'the'second purification, which is the one with which the present'application is concerned,.the 1-amino-2 chlor-anthraquinone comes out first and moreover it comes out from acid as strong as 70%.

The invention in brief consists in a method of preparing substantially pure 1-amino-2 chlor-anthraquinone which comprises mixing 1 part of crude I-aminO-Z-chIOr-anthrm: quinone with suflicient concentrated sulphuric acid to dissolve it at a temperature of about 90 (3., and heating the mixture to that approximate temperature, adding water to reduce the strength of acid to about 70%;

cooling to about 80 C. andfiltering at substantially this temperature. I In carrying the invention into effect in one form by wayoflexample, lpart of crude 1 7 amino-2-chlor-anthraquinone as referred to lo herein is dissolved in 4 parts of concentrated 1 V sulphuric acid (94-97 per cent.) at 90 C. The solution is dilutedat thistemperature with water so as to bring the strength of the acid down to 7 per cent. sulphuric acid. It s I is then allowed to cool to 80 C; and kept at this temperature until the sulphate of pure 1 amino 2-chlor anthraquinone separates out. .Suflicienttime, is then allowed forthe material to crystallize (say about half to one hour), and the sludge is filtered quickly at the same temperature.- If crystallization does not start immediately the solution is. seeded I with some of the pure compound. c 7

The cake is washed with hot 7 0 per cent.

tered and washed free from acid. g The crude 1-amino 2-ch1or-anthraquinone referred to herein may for example be such as results from the process-of ring-closing 3- V so amino-4"-chlor-2-benzoyl-benz0ie acid with sulphuric acid followed byvdilution for'the 1 separation of the major part of the content of 2-amino 3schlor-anthraquinone in which case it may contain some2-amino-3 chlorag'anthraquino'ne with other impurities. .7 H-aving'now described our invention, what we claim as new and desire to secure by LettersPatent is 7 The step in a method of preparing sub- 40 stantially pure 1'-amino-2-chlor-anthraquinone, which comprises mixing 1 part of crude 1 7 amino- 2 chlor-anthraquinone with sufficient concentrated sulphuric acid to dissolve it at a temperature of about 90 (3., heating the, mixture to that approximate temperature; adding waterto reduce the strength of acid to about cooling to about C.

filtering at substantially this temperature; r r

7 50 In testimony whereof we have signed-our names to this specification. v

WILLIAM GRAHAM WOODCOCK. 1 nu'cn ALBERT'EDWARD mascara.- .55 lv ERNEST enous]: 'sscxmr.

' -J.THOMAS.'V

2 sulphuric acid, then boiled with water, fil- 

